There are various techniques and devices for storing and archiving data and in particular for large amounts of data. The earliest storage devices were punched paper cards, which were used as early as 1804 to control silk-weaving looms. Later on, punched paper tapes were widely used for computing. Today, modern storage devices include all types of disk and tape drives. The capacity on the used recording medium is rather limited. Known are magnetically coated strips of plastic on which the data can be encoded. Storing data on tapes is considerably cheaper than storing data on disks. Tapes have usually storage capacities, ranging from a few hundred kilobytes to several gigabytes. However, the access to data on tapes is much slower than accessing data on disks.
For example, today's half-inch tapes, available as 9-track reels or as cartridges, have a capacity of 60 MB to 400 MB, quarter-inch cartridges (QIC tapes) have a capacity of 40 MB to 5 GB, and DAT (Digital Audio Tape) cartridges have a capacity of 2 GB to 24 GB, but they all require relatively expensive tape drives. Since most of the storage media bases on a magnetic recording technique, the storage media are not resistant against influencing magnetic fields. For mobile storage application a small form factor is important which with current devices and media is not achieved.
The development of scanning tunneling and atomic force microscopes has led to storage systems which make use of parallel local probes. An atomic force microscope (AFM)-based data storage concept is described in “The Millipede—More than one thousand tips for future AFM data storage”, Vettiger et al., IBM Journal of Research and Development, Vol. 44 No. 3, May 2000.
There is a clear demand for single storage devices having storage capacity of more than 1 Terabit. It is further important for such a storage device, in particular when being used in a multimedia system where image frames need to be retrieved in a fast and consecutive manner, that very high data rates (read/write speed) can be achieved. Other important aspects are power consumption, overall weight and size, reliability, data security, and shock resistance (if used in portable computer systems).
It is an object of the present invention to overcome the disadvantages of the prior art. It is another object of the present invention to provide an apparatus and method for storing and reading high data capacities.